JP2004093566A - Apparatus and method for discharging chemical liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple, inexpensive and reliable solution for determining the quantity of a liquid chemical product remaining in a container. <P>SOLUTION: The method is a method for measuring the quantity of a chemical liquid 26 remaining in a container 10. The container is connected to a means for making the chemical liquid flow from the container to a used location or the other container 24. Weight P<SB>i</SB>of the liquid in the container is measured at time t<SB>i</SB>(i is variable from 0 to n). The measurement is repeated at a time t<SB>i+1</SB>, a time t<SB>i+2</SB>and a time t<SB>n</SB>(n is an integer larger than 3). A weight change ΔP<SB>i</SB>=P<SB>i</SB>-P<SB>i+1</SB>between the time t<SB>i</SB>, t<SB>i+1</SB>is measured for Δt=t<SB>i-1</SB>-t<SB>i</SB>. When ΔP<SB>i</SB>becomes smaller than a preset fraction F of weight of the container and/or initial weight of the liquid accommodated in the container, a signal S which seems to express that the container becomes empty, is generated. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an apparatus and a method for discharging a liquid chemical product. The invention is also particularly directed to a method for measuring the amount of liquid in a container, the container being connected to means for flowing the liquid from the container to the point of use, The weight P _{i of the} liquid is measured at time t _i (i varies from 0 to n), this measurement being at time t _{i + 1} and at time t _{i + 2} , time t _n (n is an integer greater than 3) )) Until the method is repeated.

Conductive, semiconductor or dielectric layers (which may have different dielectric constants) are successively selected using a layer to mask a given surface, selectively, typically a silicon substrate or wafer. In the manufacture of semiconductors deposited on semiconductors, the layers are increasingly formed by supplying chemical liquids, referred to as "precursors," to predetermined points on the surface. Such a liquid reacts with another substance, for example a gas, also introduced into the reactor, with the temperature and pressure in the reactor in which the wafer is located, at a predetermined temperature and pressure. It is currently common practice to form a dielectric layer of SiC or SiOC using a precursor such as methylsilane (4MS), dimethyldimethoxyssilane (DMDMOS) or TMCTS. A Kutesu. These precursors, in the state of normal temperature and pressure, is a chemical product liquid.

先 Such precursors have very high added value and are commonly contained in small containers (typically up to 20 liters in volume). The container for these liquid sources is one or more containers that ensure the supply to the user's equipment. For cost reasons, it is important to optimize the use of precursors in liquid source containers to control the final loss associated with returning containers still containing product to the supplier. It is. To this end, the choice of technique for measuring the amount remaining in the container of the fluid source is of primary importance.

Many techniques for determining the presence of liquid in a container with high or low accuracy are now known. In general, the following techniques may be described.

{1. Absolute weight detection. Although this method is absolutely dependent on the reliability of the weighing device, this device is not optimal, as is well known.

{1. Float detection in the inner container of a cone whose lower part can be connected to a weighing device. This method has the risk of contamination and corrosion and does not allow for optimal use of the product, since the measuring device is brought into contact with the precursor.

{1. Ultrasonic measurement in the discharge line at the outlet of the container, which can be coupled to a measuring device. Although this method can be used for all products contained in containers, it requires fine adjustment of the equipment, which has drawbacks depending on the nature of the products, and furthermore, The use has the disadvantage of being quite costly.

{1. Detection by capacitance or optical sensor. These methods require that a drum containing the product be provided with a detection window or side detection tube.

全 て All of the above known methods generally have in common. That is, they are not practically usable for the chemical product until the last drop.

This means that the cost of the liquid chemical product used does not have to justify the existence of elaborate measures to save a few grams of product, and in general, weighing devices (balance; use of the container, even if the container is the same and is envisaged for the high relative accuracy of a measuring device that supports tens of kilograms of weight, e.g. This is because inaccuracy in weight in relation to weight has proven to be sufficient.

The method of the present invention can solve the problems of the prior art and provide a simple, low cost and reliable solution for determining the amount of liquid chemical product remaining in a container. provide.

The method according to the invention is such that the change in the weight of the liquid ΔP _i = P _i −P _{i + 1} between time t ₁ and time t ₂ is measured to generate a signal S at time t _n, which signal S is Indicating that the container may be considered empty when ΔP _i is less than a predetermined fraction F of the weight of the container and / or the weight of the first liquid contained in the container, Is the way. Where i is variable from 0 to n, where n is the time tn at which the (n + 1) th ΔP _i measurement sampling occurs, and ΔP _i is the weight of the container and / or the first It will be defined to be the time determined for the first time when the liquid weight is less than a preset fraction F. The value of the fraction is set in advance.

Preferably, the measurement of the weight change ΔP _i is such that the value of the direct or indirect measurement of the weight of the container and / or the liquid is less than or equal to a predetermined fraction F of the initial weight of the container and the liquid contained in the container. Only when it becomes. Generally, the predetermined fraction is no more than 10% of the initial weight of the container and / or the liquid initially contained in the container (or the weight of the container and the weight of the liquid initially contained in the container). It is.

Throughout the description of the invention, reference is made in general to the weight Pi of the liquid in the container, ie to the weight of the liquid remaining in the container at time ti. The initial weight of the liquid (together with or separate from the weight of the container itself) is the weight of the liquid when the container (also called the shuttle drum) is replaced. At the time t _{0 when} sampling begins, the weight P ₀ will generally be no longer (but low) the initial weight of the liquid.

Of course, as a general rule, the total weight of the container, ie the weight of the container itself plus the total weight of the filling, will be measured at two consecutive times t _i and t _{i + 1} . This measurement is equivalent and equivalent to measuring the change in weight of the liquid in the container between these two consecutive times. Those skilled in the art can make the necessary changes to the measurements. As a result, if an actual measurement is taken, a change in this measurement is equivalent to a change in the weight of the liquid in the container.

If Kakaware to variations of the present invention, the weight of the container and / or liquid (at time t _i and t _{i + 1)} the time interval between two successive measurements is set in advance, preferably, 10 seconds.

Preferably, the flow of the liquid is provided by a pressure created by a pressure gas present above the level of the liquid in the container, the gas having a purity compatible with the purity of the liquid. This gas will be essentially a gas that is substantially inert to the propelled liquid. The term “compatible purity” is understood to mean a purity that does not increase the concentration of impurities (particles or species such as H ₂ O, solvents, etc.) in the liquid. In addition, the gas having a pressure that causes the liquid to drain from the container should preferably have a minimum solubility for the propelled chemical liquid. Those of ordinary skill in the art will generally be able to quickly determine the solubility of the gas in the propelled liquid by literature or simple tests. As a general rule, the gas is most preferably helium (having so-called "electronic purity" to satisfy the above regulations).

According to a modification of the present invention, the liquid is sent to the second container before being sent to the point of use.

Generally, the propellant gas is selected from helium, neon, xenon, nitrogen, argon, krypton, and / or carbon dioxide (preferably, helium is generally selected). The gas preferably has a pressure of 10 ⁵ to 10 ⁶ Pascals. Generally, the propellant gas is stored in a container, such as a bottle, at a predetermined pressure in gaseous form, but in some cases, initially in a liquid form, such as liquid nitrogen and / or argon. It can be assumed that gas is supplied. This can evaporate above the liquid precursor to produce the required pressurization.

The present invention also provides a container for containing a chemical liquid to be dispensed, means for connecting this container to a point of use where the chemical liquid is used, and measuring means for measuring the amount of liquid in said container comprising the door, the measuring means, consecutive time t _i, such as t _{i + 1,} these time t _i, t _{i + 1} measurements P _i of the amount of chemical liquid or the _like, P _{i + 1,} etc. Means for generating a signal to start the operation, means for storing the measurements P _i , P _{i + 1} , etc. of the amount of the chemical liquid at the times t _i , t _{i + 1} , respectively, and a time t t means for calculating the difference in the amount of chemical liquid ΔP _i = P _i −P _{i + 1} between _i and time t _{i + 1} , means for comparing this ΔP _i with a preset value F, ΔP _i > A first signal S1 is generated when F is satisfied, or a second signal S2 is generated when ΔP _i ≦ F is satisfied. For ejecting a chemical liquid, comprising means for ejecting a chemical liquid.

FIG. 1 shows a curve of the relative passate change of the weight of a liquid (under gas pressure as described above) in a container as a function of time, which shows that at time t = 0, 7% Indicates that an initial weight of liquid remains. On the left side of FIG. 1, the curve starts at a relative time t = 0, with a weight value P ₀ equal to an initial weight of 7%. The discharge curve for a moving drum, ie a shuttle drum (see FIG. 2), is a straight line that decreases uniformly according to the representation given in FIG.

The transfer from the mobile container 10 to the stationary container 24 (or point of use if only a single container is used) is done here with a gas (eg, helium) that is electronically pure and difficult to dissolve in a liquid. You. This gas is at a sufficient pressure (usually several bar, to allow the chemical liquid to rise up the dip tube 20 by the pressure). The wicking tube extends as far as possible to the bottom of the container and is often longer than necessary to reach the bottom of the container, allowing the lower end to be located at the bottom of the container. Preferably, the cross section of the lower end of the tube is sloped, the longest part of the slope being supported on the bottom of the container to collect all of the last part of liquid when the drum is empty Can be done.

Since there is a constant overpressure above the chemical liquid which is much higher than the pressure due to the height of the liquid in the container, a substantially constant pressure develops at the lower end of the wicking tube and at point 4 Curve (FIG. 1). This point 4 is shown at time t ₃ (FIG. 1), where the lower end of the wicking tube is no longer completely immersed in the liquid, so that the propellant gas is Is sucked into and a small amount of chemical liquid is transferred. Thus, curve C, tends to be decreased rapid is not, the the next sampling time t _4, the curve C does not reach the point that would have reached if you keep linearly decreasing. According to the invention, the container must be considered empty after this time. On the other hand, according to the prior art, this level cannot generally be determined exactly.

(To avoid the risk of emptying the line from the wicking tube, the conventional method has a level of 5% of the remaining product as a limit that may need to be replaced with a container containing the chemical liquid. (Set limit value) is generally set, which means that not a small percentage (2 to 4%) of the liquid chemical product is discarded. In other words, it allows the use of a small amount of the remaining chemical products while avoiding the risk to consumers emptied at the point of use.

Starting from point 1 at time t = 0, the point 2 on the curve, it is reached after a time t ₁ which is arbitrarily determined so as to initiate the process of monitoring the contents of the moving drum. This step may begin immediately at time t = 0, according to a preferred method of practicing the invention. However, it is desirable in some cases to start this process when P _i has simply reached a predetermined preset value. The ΔP _i value is then sampled at all of the time intervals Δt, so as to be described later, in a controlled manner in a regular (preferably), irregular or controlled manner by other parameters. Measured correctly using a weighing device (balance). Thus, point 3 on curve C is reached at time t ₂ = t ₁ + Δt, point 4 on the curve is reached at time t ₃ = t ₂ + Δt, and point 5 on the curve Is reached when the measurement indicates that the .DELTA.P value has become less than would be expected if the slope of the curve C followed by a uniformly decreasing slope. This indicates that the drum is empty or practically empty (when ΔP is less than a preset value), and thus it is time to replace this drum. Experience has shown that the point of curvature 5 depends on the container, the wicking tube, etc., and this will vary depending on the environment according to the physical parameters of each container and each wicking tube. Teaches that whenever a chemical liquid drum is installed, it will not drop below an unforeseen predetermined percentage by weight.

FIG. 2 shows an example of an embodiment of the method according to the invention and of an implementation system in which the same elements in the other figures have the same reference numbers. The moving drum 10 is connected by a line 11 via a valve 9 to a line 13 and a storage means (tank) 14 for pressurized gas. This gas is preferably an inert gas, especially helium, for example when nitrogen and / or argon reacts with the liquid chemical product. Helium has the effect that it is practically completely inert to all products. The helium 15 is stored in a tank 14, which is also connected to a fixed drum 24 via a line 31, a valve 33 and a line 28. A weight measuring device (balance) 19 provided with a weight measuring means (balance measurement and control system) 40 is provided below the moving drum 10. Inside the moving drum 10 there is a liquid chemical product at the bottom. A tube 20 is inserted into the product, which tube moves the product to the stationary drum 24. An inert gas (helium) 16 at a pressure P ₁ is present on the liquid surface 18 of the liquid chemical product. This inert gas thus pressurizes the liquid chemical product so that the liquid chemical product can be transferred to the stationary drum 24. A line 12 functioning as a vent is connected to the line 11 via a valve 8. As a result, the pressure of the inert gas in the moving tank 10 can be adjusted. Pressure sensor 21 is, in the line 20 from the mobile container (tank) 10 is provided for measuring the pressure P ₁ of not moving Nko. This line 20 is connected to the line 23 via a valve 23. This line 23 makes it possible to replenish the chemical product when the liquid chemical product 26 in the fixed drum 24 reaches a low level LL or a very low level VLL. By filling the stationary drum 24 with a liquid chemical product, the liquid level of the chemical product 26 can be raised from a low level LL or a very low level VLL to a high level HL or a very high level VHL. During this time, an inert gas such as helium is maintained above the fixed container (drum) 24. A pressure sensor 29 for measuring the pressure in the fixed drum 24, a branch line 30, and a valve 32 are connected to the line 28. This valve is to control the pressure P ₂ of the stationary drum 24, serves to exhaust.

A line 34, a valve 35, and a line 36 are sequentially connected to the base of the fixed drum 24, so that the liquid chemical product can be discharged to the equipment 37. During operation, (measured safety redundancy and high level to a low level) so that the pressure P ₁ in the mobile drum is higher at all times than the pressure P ₂ in the fixed drum is preferably maintained.

The operation of the system shown in FIG. 2 is described below under normal running conditions.

In this case, the product is discharged by pressing the fixed drum 24. The filling of the fixed drum is started when the low level LL is reached. To this end, the product is transferred from the moving drum 10 without disturbing the discharge to the equipment via the line 34, the valve 35 and the line 36. Then, the filling of the fixed drum 24 is automatically stopped as soon as the high level HL is reached. The very low level VLL and the very high level VHL are not used as detection levels for normal operation, but may be used only as a warning level particularly requiring a sudden stop or a rapid filling process. You will understand.

If the chemical product for filling a fixed drum that is being filled is no longer sufficient in the moving drum 10, a system for detecting the end of the product in the moving drum 10 is shown in FIG. , The operation of filling the moving drum can be started. To detect the end of this moving drum, two parameters that can be changed by the operator can be used for this purpose. This, for example, between times t1 and t2, is the time interval Δt such (see Figure 1) between times t2 and t3, and the weight change [Delta] P _i between two set time. This weight change can be the absolute value change ΔP _i or the relative value change ΔP _i / P (as described above, as a percentage of the initial weight). The operator can pre-store in the balance measurement and control system 40 the minimum threshold that the parameter ΔP _i or ΔP _i / P must not reach. When a value below this level is detected, an alarm signal such as a display, siren or the like can be generated.

According to a variant of the invention, it is possible to provide a configurable (eg 5%) threshold advance warning system for the parameters associated with the parameter ΔP _i / P. When this change is less than 5%, the operator's attention is redirected by a pre-warning, pre-siren, etc. Preferably, the amount of product contained in the moving drum is constantly displayed on the screen of the system 40. This may be expressed as a unit of weight, and / or a unit of volume, and / or as a percentage. The empty drum detection method can use any weight derivation unit, including those described above. In practice, it is preferable to use measurements expressed as a percentage. In this case, the time interval Δt is typically 10 to 30 seconds, and the weight change criterion is typically 0.5% (absolute value). The empty drum detection method also makes it possible to monitor the relative change in weight over the time interval Δt. Of course, in this case, the weight change criterion must be applied. Generally, if absolute or relative liquid weight changes are monitored, the weight of the moving drum 10 is not directly included in the measurement and must simply be reduced. In particular, if a variable absolute value is used, it will be assumed as a general rule that the weight of the empty drum is always the same.

Of course, the system shown in FIG. 2 includes a plurality of fixed drums and a plurality of moving drums, and each moving drum includes a weight measuring system as described with reference to FIG. Is also applicable. Thus, the system described in FIG. 2 can significantly prevent the measurement that the drum must be empty and accurate, the force applied by the tubing connecting the discharge system to the moving drum, the drift in balance and Problem can be solved.

FIG. 3 shows an example of a flowchart for operation of the method and apparatus according to the present invention.

Of course, other operating systems are possible and this system is simply given by indication.

At time t = t ₀ , corresponding to the detection of the low level LL in the stationary drum, filling of the stationary drum and monitoring of the weight of the liquid in the moving drum are started simultaneously, as disclosed in the present invention. Filling continues (loop through point A in FIG. 3) until a high level HL in the fixed drum is detected, similar to monitoring the weight in the moving drum. After several loops (described below), the state is as at time t = t _i. The first operation is to store the weight P _i remaining on the moving drum. This operation is repeated at time t _{i + 1} = t _i + Δt, when the remaining weight p _{i + 1} is also stored. Weight change _{ΔP i = P i -P i +} 1 during the time interval Delta] t _i is, is calculated and compared to a predetermined value K. If the [Delta] P _{i> K} during a time interval Delta] t i _(moving drum available), the signal S ₁ is generated. In this case, the monitoring of the weight is continued according to the loop shown in FIG. 3 (repeated i = i + 1). If ΔP _i > K or ΔP _i = K during the same time interval Δt _i , a signal S2 is generated (the moving drum is empty).

Thus, comparison is t _i and t _{m (t m} is preprogrammed operation end time) is made between the. If if _t i _{<t m, t i} is replaced with _{t i} and _{t m} in a loop operation is restarted. If not, the operation is terminated. The value of Delta] t _i and K are predetermined, i.e., it is obvious that pre-selected by the user.

Examples The following examples illustrate the method of the present invention based on the following data.

　１．ｔ＝２２５秒でのからドラムの検出
ＮＢ：移動ドラムが空とされたときに、バランスは、移動ドラム内の１．０％の製造物の残量の存在を示す。このことは、バランスの相対精度と、移動ドラムに接続するための配線により生じる力との累積影響を示す。ここで、前記力は、移動ドラムの見かけ上の重量を増す傾向がある。しかし、上記実施例は、これら２つの影響は、本発明の方法に係わる空のドラム検出の信頼性に対して関係のないことを示す。 1. The moving drum, when full, will contain 20 liters of product 1.2 Low level LL detection on fixed drum when 2.52.5% product remains on moving drum 0.5 bar pressure gradient Time interval Δt _i = 15 seconds 1. Detection limit of the air of the drum, the weight change between the Δt _i <0.5%
1. The weight values of the liquid remaining in the moving drum are given in Table 1 below.

1. Drum detection at t = 225 seconds NB: When the moving drum is emptied, the balance indicates the presence of 1.0% product remaining in the moving drum. This indicates the cumulative effect of the relative accuracy of the balance and the force generated by the wiring for connecting to the moving drum. Here, the force tends to increase the apparent weight of the moving drum. However, the above example shows that these two effects are not relevant to the reliability of empty drum detection according to the method of the present invention.

Figure 4 shows a curve in which the relative change in the weight of the container during use of the liquid is shown as a function of time. Diagram showing part of a system implemented to supply liquid to an integrated circuit manufacturing reactor having a moving container (shuttle drum) that changes regularly when emptied and a fixed container that is the buffer container of the plant. It is. 4 is a flowchart for an apparatus and method according to the present invention.

Explanation of reference numerals

Reference numeral 10: moving container (drum), 14: tank, 15: helium, 16: inert gas (helium), 19: weight measuring device (balance), 20: suction tube, 24: fixed container (drum), 26 ... Liquid chemical products

Claims (10)

A method for measuring the amount of liquid in a container, the container being connected to means for flowing the liquid from the container to a point of use, wherein the weight P _i of the liquid in the container is determined by time. measured at t _i (i varies from 0 to n), and this measurement is repeated at time t _{i + 1} and at time t _{i + 2} until time t _n (n is an integer greater than 3), where , The weight change ΔP _i = P _i −P _{i + 1} between times t _i and t _{i + 1} is measured under Δt = t _i−1 −t _i , where ΔP _i is the weight of the container and / or A method wherein the container is measured to generate a signal S when the weight of the first liquid contained in the container falls below a predetermined fraction F, which can be considered as empty of the container. The weight change ΔP _i is measured when the value of the direct or indirect measurement of the weight of the container and / or the liquid is less than or equal to a predetermined fraction F of the initial weight of the container and the liquid contained in the container. 2. The method of claim 1, which can only be started. 3. The method of claim 2, wherein the predetermined fraction is no more than 10% of the initial weight of the container and / or the liquid initially contained in the container. 4. The method according to claim 1, wherein the time interval Δt _i = t _{i + 1} −t _i between two successive measurements of the container and / or the liquid is preset, preferably about 10 seconds. 5. The liquid flow of claim 1, wherein the flow of the liquid is provided by a pressure generated by a pressure gas present on a liquid surface of the liquid in the container, the gas having a purity compatible with the purity of the liquid. Method. 6. The method of claim 5, wherein said gas is a gas that is substantially inert to the liquid being propelled. 7. The method of claim 5 or 6, wherein the liquid is sent to a second container before being sent to the point of use. 8. The method according to claim 5, wherein the gas is selected from helium, neon, xenon, nitrogen, argon, krypton, and / or carbon dioxide. The gas is 10 ⁵ to any one of the methods of claims 5 to 8 with a pressure of ¹⁰⁶ Pascals. A container for storing the chemical liquid to be discharged, means for connecting the container to a point of use where the chemical liquid is used, and measuring means for measuring the amount of liquid in the container, measuring means, generating consecutive time t _i, etc. t _{i + 1,} these time t _i, t _{i + 1} measurement of the amount of chemical liquid or the like P _i, a P _{i + 1,} the signal to initiate and clock means for the time t _i, t _{i + 1} the amount of measurement P _i of the chemical liquid or the _like, and means for P _{i + 1,} etc. respectively stored, and the time t _i and time t _{i + 1} Means for calculating the difference in the amount of chemical liquid ΔP _i = P _i −P _{i + 1} between the above, a means for comparing this ΔP _i with a preset value F, and a means for calculating the difference when ΔP _i > F. A means for generating the second signal S2 when the signal S1 is 1 or ΔP _i ≦ F. For discharging chemical liquids.

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